What is Diabetes Mellitus?

Last Updated: September 26, 2023

About 422 million people worldwide have diabetes, the majority living in low-and middle-income countries, and 1.5 million deaths are directly attributed to diabetes each year —This is stated by the World Health Organization, and even though there are multiple treatment options for the disease, these numbers are, unfortunately, still on the rise.1 This articles talks more about types of diabetes and symptoms of diabetes.

About Diabetes Mellitus

Diabetes mellitus is an illness that affects how the body metabolizes carbohydrates. Carbohydrates are one of three main macronutrients (along with proteins and fats) that make up the food we eat, and they’re often referred to as “carbs.” Carbs are broken down into simple sugars in the digestive system and absorbed into your bloodstream.2

For your body to use these carbs as fuel, they need to be converted into glucose. This happens in two different ways:

  • Your pancreas releases a hormone called insulin that helps move glucose from the blood vessels into cells where it can be stored (in the liver in the form of glycogen) or used for energy production (in the cells).
  • The liver breaks down glycogen (a special kind of starch), which it stores until needed by a cell.

Insulin is a special hormone that helps sugar (glucose) get into the body’s cells. After this happens, the sugar can be used to create energy. But sometimes the body has a problem with insulin and makes too little or none at all. This can lead to diabetes, a disease where your blood glucose levels are too high.

What Are the Different Types of Diabetes?

When you have diabetes, your pancreas does not make enough insulin or does not make any at all, these can be due to different reasons, better explained by knowing the three main types of diabetes, and these include the following:3,4

Type 1 Diabetes Mellitus:

Type 1 diabetes, also called juvenile diabetes or insulin-dependent diabetes is a chronic condition caused by the immune system destroying beta cells in the pancreas that make insulin (insulin-dependent).

It’s considered an autoimmune disease because the body’s immune system attacks its beta cells. When these cells are destroyed and can’t produce enough insulin to meet your body’s needs, you have type 1 diabetes.

Since people with type 1 diabetes do not have any insulin-producing cells in their bodies, they need to take daily shots of insulin to control their blood sugar levels.

Some type 1 diabetes patients may need daily injections of insulin to stay alive and avoid serious health problems like high blood pressure, nerve damage, or kidney disease (all of which can lead to heart attacks or strokes). Others may need injections only when they eat carbohydrate foods such as bread or pasta because their bodies don’t respond properly to the amount of food they eat; this is called eating too much carbohydrate at one time (carbohydrate overconsumption).

Type 2 Diabetes Mellitus:

Type 2 diabetes mellitus is considered the most common type of diabetes. Exactly why this happens is unknown, although genetics and environmental factors, such as being overweight and inactive, seem to be contributing factors.5

When you eat or drink something sugary, your body breaks it down into glucose. In people with type 2 diabetes, the pancreas does not make enough insulin, or when the body becomes resistant to insulin. Sometimes this happens because of obesity, but other health problems can also cause type 2 diabetes.

Excess weight is a major risk factor for type 2 diabetes because it can lead to insulin resistance and an increased risk of developing prediabetes (borderline diabetes). Other environmental factors that may increase your chance of getting type 2 diabetes include:6

  • Smoking
  • A family history of the disease
  • Obesity7
  • Physical inactivity
  • High blood pressure
  • Old age (over 45 years old)

Gestational Diabetes:

This type of diabetes occurs in women who are pregnant (these women may have no previous history of diabetes). This is generally due to the changes happening in a woman’s body during this time that they become resistant to insulin.8

After delivering the baby, most women’s blood sugar level return to normal and they don’t suffer from diabetes anymore. However, 50% of women go on to develop diabetes mellitus type 2. Thus, it’s very important to be on the lookout for gestational diabetes and to consult your doctor on how to prevent it from developing into type 2 diabetes long after you have your baby.

How Do You Test for Diabetes Mellitus?

To get a conclusive diagnosis of diabetes mellitus, doctors usually prescribe one or more of the following tests:9

Fasting Plasma Glucose test. This tests your blood glucose level after 8 hours of fasting (no food or drinks), only water is allowed.

Random Plasma Glucose test. This tests your blood glucose level at any time, no fasting is needed.

A1c/HbA1C or Glycated Hemoglobin test. This quantifies the amount of glucose attached to your hemoglobin (hemoglobin is the protein prominently present in your blood and carries oxygen). This test provides information about your accumulated blood glucose level for the duration of two-to-three months.

Oral Glucose Tolerance test. This tests your blood glucose level after fasting, then three times after drinking something sugary (one hour after each test).

What is Prediabetes?

Prediabetes, also called borderline diabetes, is a condition where a person’s blood sugar levels are higher than normal, but not high enough to be considered type 2 diabetes.10

If you have prediabetes, it is critical that you take steps to lower your blood sugar levels.11 Otherwise, you will likely develop type 2 diabetes.12 If left untreated, prediabetes can lead to diabetes which eventually leads to other health problems including the following:13

  • Heart disease
  • Kidney disease
  • Nerve damage
  • Eye damage
  • Foot damage
  • Strokes
  • Alzheimer’s disease
  • Infections

According to the Centers for Disease Control and Prevention (CDC), “In the United States, 96 million adults—more than 1 in 3—have prediabetes. More than 8 in 10 of them don’t know they have it. With prediabetes, blood sugar levels are higher than normal, but not high enough for a type 2 diabetes diagnosis. Prediabetes raises your risk for type 2 diabetes, heart disease, and stroke. But there’s good news.”14

Symptoms and Warning Signs of Diabetes

Symptoms of diabetes mellitus generally differ from patient to patient depending on various factors and these include the following:

  • Type of diabetes
  • Age
  • Medical history
  • Overall health
  • Any underlying medical conditions

While symptoms of type 1 diabetes appear quickly, patients with type 2 diabetes may appear asymptomatic for years with very mild symptoms that develop slowly. Some patients with type 2 diabetes get diagnosed very late when they have a diabetes-related complication (ex. heart disease).

That being said, you should be on the lookout for the following warning signs of diabetes:

  • Frequent urination
  • Excessive thirst
  • Numbness and tingling in the hand or feet
  • Wounds and sores that don’t heal quickly
  • Unexplained weight loss
  • Fatigue and tiredness
  • Increased hunger
  • Blurry vision

Treatment Options for Diabetes Mellitus

Although there is no cure for diabetes mellitus, there are many treatment options and lifestyle changes you can apply to help you manage the condition and improve your quality of life.15

  • Patients with type 1 diabetes mellitus

These patients require taking insulin consistently as their bodies are unable to make it on their own. They may even take it several times a day depending on how much they eat or drink to control their blood glucose levels.

  • Patients with type 2 diabetes mellitus

These patients have a wide range of treatment options, some may control their blood glucose level by adding healthy food and exercising regularly. Others may need to manage their blood sugar levels by taking pills or insulin shots.

  • Patients with gestational diabetes

Similar to patients with type 2 diabetes, women who suffer from gestational diabetes may be able to control their blood sugar levels by eating healthily or taking insulin (insulin is safe for pregnant women).

Healthy lifestyle changes have also proven very effective in managing diabetes mellitus in patients. In fact, a study published in the Canadian Journal of Diabetes, in 2018, reports that “For people with type 2 diabetes, supervised exercise programs have been particularly effective in improving glycemic control, reducing the need for noninsulin antihyperglycemic agents and insulin, and producing modest but sustained weight loss.” This subsequently means that exercise plays an important role in controlling diabetes and may be used as an independent or adjuvant therapy depending on each patient.15

No matter what type of diabetes mellitus you have, it’s best to always follow up with your doctor so that they can set up the most suitable treatment plan for your condition. Consulting your doctor first before making any decisions helps with avoiding unwanted complications.


Diabetes is a chronic disease in which blood glucose (sugar) levels are above normal. There are three main types of diabetes, type 1, type 2, and gestational diabetes. In type 1 diabetes, the pancreas does not produce any insulin. In type 2 diabetes, either your pancreas does not make enough insulin, or your body cannot effectively use the insulin it makes, in gestational diabetes, a woman’s body is resistant to insulin.

There’s no cure for diabetes, but with the right formula of lifestyle changes and treatment, it can be managed without difficulty.



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2.        Egan AM, Dinneen SF. What is diabetes? Medicine. 2019 Jan 1;47(1):1–4. Available from: https://www.niddk.nih.gov/health-information/diabetes/overview/what-is-diabetes

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7.        Chia CW, Egan JM. Incretins in obesity and diabetes. Ann N Y Acad Sci [Internet]. 2020 Feb 1 [cited 2022 Oct 23];1461(1):104–26. Available from: https://onlinelibrary.wiley.com/doi/full/10.1111/nyas.14211

8.        McIntyre HD, Catalano P, Zhang C, Desoye G, Mathiesen ER, Damm P. Gestational diabetes mellitus. Nature Reviews Disease Primers 2019 5:1 [Internet]. 2019 Jul 11 [cited 2022 Oct 23];5(1):1–19. Available from: https://www.nature.com/articles/s41572-019-0098-8

9.        2. Classification and Diagnosis of Diabetes: Standards of Medical Care in Diabetes-2022. 2021 [cited 2022 Oct 23]; Available from: https://doi.org/10.2337/dc22-S002

10.      Khan RMM, Chua ZJY, Tan JC, Yang Y, Liao Z, Zhao Y. From Pre-Diabetes to Diabetes: Diagnosis, Treatments and Translational Research. Medicina 2019, Vol 55, Page 546 [Internet]. 2019 Aug 29 [cited 2022 Oct 23];55(9):546. Available from: https://www.mdpi.com/1648-9144/55/9/546/htm

11.      Papatheodorou K, Banach M, Bekiari E, Rizzo M, Edmonds M. Complications of Diabetes 2017. J Diabetes Res. 2018;2018. Available from: https://pubmed.ncbi.nlm.nih.gov/29713648/

12.      Harding JL, Pavkov ME, Magliano DJ, Shaw JE, Gregg EW. Global trends in diabetes complications: a review of current evidence. Diabetologia [Internet]. 2019 Jan 1 [cited 2022 Oct 23];62(1):3–16. Available from: https://link.springer.com/article/10.1007/s00125-018-4711-2

13.      Cole JB, Florez JC. Genetics of diabetes mellitus and diabetes complications. Nature Reviews Nephrology 2020 16:7 [Internet]. 2020 May 12 [cited 2022 Oct 23];16(7):377–90. Available from: https://www.nature.com/articles/s41581-020-0278-5

14.      Center for Disease Control and Prevention (CDC). Gestational Diabetes | CDC [Internet]. 2022 [cited 2022 Oct 23]. Available from: https://www.cdc.gov/diabetes/basics/gestational.html

15.      Sigal RJ, Armstrong MJ, Bacon SL, Boulé NG, Dasgupta K, Kenny GP, et al. Physical Activity and Diabetes. Can J Diabetes [Internet]. 2018 Apr 1 [cited 2022 Oct 23];42:S54–63. Available from: http://www.canadianjournalofdiabetes.com/article/S1499267117308183/fulltext

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